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South-Eastern Spain is a key locality of the Western Mediterranean to unravel the origin of post-collisional magmatism and its relationships with the multi-stage evolution of the upper mantle in complex geodynamic settings. This study is focused on the Plio-Pleistocene post-collisional intraplate-like alkali basalts cropping out in the Tallante area (South-Eastern Spain) that are erupted in a region previously characterised by subduction related calc-alkaline to ultrapotassic (i.e., lamproitic) volcanism. Tallante alkali basalts represent a volcanic episode similar to other contemporary small volume intraplate volcanic occurrences of Western-Central Europe and North Africa, which are believed to derive from a Common Mantle Reservoir characterising the entire Circum Mediterranean asthenosphere. We report new major, trace element, and Sr-Nd-Pb isotope data on Tallante alkali basalts, showing compositions broadly similar to the other mafic volcanic rocks derived from the Common Mantle Reservoir and thus suggesting an asthenospheric component similar to other European within plate volcanic rocks. On the other hand, specific trace element ratios, such as Ce/Pb, Nb/U, Th/Yb, along with delta207Pb/204Pb and 87Sr/86Sr, clearly indicate the involvement of an enriched, subduction-related component, with a lamproitic geochemical and isotopic flavour. The trace element ratios suggest that low melting degree magmas from the Common Mantle Reservoir infiltrated and triggered melting of the strongly metasomatised sub-continental lithospheric mantle, which produced the lamproitic magmas previously erupted in the same area. The proposed origin of Tallante alkali basalts, located along a large scale left-lateral strike-slip fault, is consistent with analytical, numerical and laboratory models indicating that narrow subduction zones such as the Gibraltar Arc are characterised by mantle inflow around the slab edges determining upwelling and adiabatic melting of the asthenospheric mantle through slab tears.

High-MgO lamproite and lamproite-like (i.e. lamprophyric) ultrapotassic rocks are recurrent in the Mediterranean and surrounding regions. They are associated in space and time with ultrapotassic shoshonites and high-K calc-alkaline rocks. This magmatism is linked with the geodynamic evolution of the westernmost sector of the Alpine-Himalayan collisional margin, which followed the closure of the Tethys Ocean. Subduction-related lamproites, lamprophyres, shoshonites and high-K calc-alkaline suites were emplaced in the Mediterranean region in the form of shallow level intrusions (e.g. plugs, dykes and laccoliths) and small volume lava flows, with very subordinate pyroclastic rocks, starting from the Oligocene, in the Western Alps (northern Italy), through the Late Miocene in Corsica (southern France) and in Murcia-Almeria (southeastern Spain), to the Plio-Pleistocene in Southern Tuscany and Northern Latium (central Italy), in the Balkan peninsula (Serbia and Macedonia) and in the Western Anatolia (Turkey). The ultrapotassic rocks are mostly lamprophyric, but olivine latitic lavas with a clear lamproitic affinity are also found, as well as dacitic to trachytic differentiated products. Lamproite-like rocks range from slightly silica under-saturated to silica over-saturated composition, have relatively low Al2O3, CaO and Na2O contents, resulting in plagioclase-free parageneses, and consist of abundant K-feldspar, phlogopite, diopsidic clinopyroxene and highly forsteritic olivine. Leucite is generally absent, and it is rarely found only in the groundmasses of Spanish lamproites. Mediterranean lamproites and associated rocks share an extreme enrichment in many incompatible trace elements and depletion in High Field Strength Elements and high, and positively correlated Th/La and Sm/La ratios. They have radiogenic Sr and unradiogenic Nd isotope compositions, high 207Pb over 206Pb and high time-integrated 232Th/238U. Their composition requires an originally depleted lithospheric mantle source metasomatized by at least two different agents: (1) a high Th/La and Sm/La (i.e. SALATHO) component deriving from lawsonite-bearing, ancient crustal domains likely hosted in mélanges formed during the diachronous collision of the northward drifting continental slivers from Gondwana; (2) a K-rich component derived from a recent subduction and recycling of siliciclastic sediments. These metasomatic melts produced a lithospheric mantle source characterized by network of felsic and phlogopite-rich veins, respectively. Geothermal readjustment during post-collisional events induced progressive melting of the different types of veins and the surrounding peridotite generating the entire compositional spectrum of the observed magmas. In this complex scenario, orogenic Mediterranean lamproites represent rocks that characterize areas that were affected by multiple Wilson cycles, as observed in the Alpine-Himalayan Realm.